a. Field of the Invention
The instant invention pertains generally to irrigated catheter devices. More particularly, the instant invention is directed toward ablation catheter tips for use in the human body, where an angled or a rotational irrigation fluid flow is generated around the ablation catheter tip, advantageously cooling the ablation electrode and targeted areas.
b. Background Art
Electrophysiology catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, a catheter is manipulated through the patient's vasculature and to the intended site, for example, a site within the patient's heart, and carries one or more electrodes, which may be used for ablation, diagnosis, or the like.
There are a number of methods used for ablation of desired areas, including for example, radiofrequency (RF) ablation. RF ablation is accomplished by transmission of radiofrequency energy to a desired target area through an electrode assembly to ablate tissue at the target site. Because RF ablation may generate significant heat, which if not controlled can result in excessive tissue damage, such as steam pop, tissue charring, and the like, it is desirable to include a mechanism to irrigate the target area and the device with biocompatible fluids, such as saline solution. The use of fluid mitigates rising temperature in and around the ablation electrode, therefore reducing the risk of unwanted tissue damage and blood coagulation.
There are typically two classes of irrigated catheter devices, open and closed ablation catheters. Closed ablation catheters typically circulate a cooling fluid within the inner cavity of the ablation catheter tip. Open ablation catheters, on the other hand, use the inner cavity of the ablation catheter tip as a manifold to distribute saline solution, or other irrigation fluids known to those skilled in the art, to one or more passageways leading to an orifice. This lowers the temperature of the ablation catheter tip by bringing the outer surface of the ablation electrode in contact with the cool irrigation fluid and dilute the blood around the electrode to prevent blood coagulation.
Because the velocity or volume flow rate of the irrigation flow is typically within the range of two milliliters per minute to twenty milliliters per minute and is thus relatively low compared to, for example, the velocity of the blood circulation inside the atrium of the heart, cooling is most effective when the irrigation flow is kept in the area close to the ablation catheter tip and accordingly the ablation electrode. However, in prior art embodiments, it was difficult to keep the flow close to the ablation electrode, as the flow was directed along a radial line away from the ablation catheter tip, therefore limiting the ability to cool. Thus, it is one object of the present invention to improve the cooling effect of irrigated catheters devices by, for example, generating an angled flow or rotational flow around the outer surface of the ablation catheter tip such that irrigation fluid is delivered, and remains, closer to the outer surface of the ablation electrode than in prior art embodiments. It is another object of the present invention to improve the cooling effect of irrigated catheter devices by insulating the irrigating chambers.